Electronic vapor provision systems, electronic nicotine delivery systems, etc., which are collectively referred to herein as e-cigarettes, generally contain a reservoir of liquid which is to be vaporized. When a user sucks or draws on the device, this activates a heater to vaporize a small amount of liquid, which is then inhaled by the user. Most e-cigarettes include a re-chargeable battery for supplying electrical power to the heater and other electrical/electronic components, such as a sensor to detect inhalation. Some e-cigarettes have a cartridge section. After the nicotine or other liquid in this cartridge has been exhausted, the empty cartridge can be removed or separated from the e-cigarette and replaced with a new cartridge containing further nicotine.
E-cigarettes are often supplied in packs for protection and easy portability. Such packs may accommodate multiple e-cigarettes and/or replacement cartridges, thereby offering a backup facility if one e-cigarette (or its cartridge) is exhausted. An e-cigarette pack may also have the ability to re-charge an e-cigarette, again helping to ensure good operating availability of the e-cigarette for a user. Such a pack may be provided with a cylindrical hole for receiving an e-cigarette for recharging, the hole generally reflecting the elongated, cylindrical shape of an e-cigarette. When the e-cigarette is located in the hole, the battery can be re-charged by a suitable wired or wireless connection (a wireless connection may rely upon induction charging). In some packs, the cylindrical hole may receive the entire e-cigarette for re-charging, while in other packs only a portion of the e-cigarette may be received into the hole.
In some devices, the pack must be connected to a power supply, e.g. a mains outlet or USB connection, during re-charging of the e-cigarette battery. In this case, the pack is typically acting as a convenient device for holding and interfacing to the e-cigarette during re-charging. In other devices, the pack itself is provided with a battery (or other charge storage facility). The pack battery allows the e-cigarette to be re-charged from the pack without the need for the pack to be connected to an external power supply during the re-charging, thereby providing greater convenience for a user.
The pack battery will be depleted in due course, and so is generally provided with its own re-charging facility—typically again reliant upon some form of mains or USB connection. However, since the pack is larger than an e-cigarette, it can accommodate a larger battery and therefore the pack does not have to be re-charged as frequently as an e-cigarette. For example, the charge capacity of a typical e-cigarette battery may be approximately 60 mAh, whereas the charge capacity of a typical pack battery might be in the region of 800 mAh. Accordingly, the pack battery is capable of re-charging the e-cigarette a few times at least before the pack battery itself needs to be re-charged.
Such a multiple or hierarchical arrangement of separately chargeable systems, namely firstly an e-cigarette and secondly a pack for the e-cigarette, is relatively rare. In contrast, most re-chargeable devices, e.g. mobile (cell) phones, are usually connected directly to a mains-powered charging supply (or else to an in-car charging supply). Furthermore, when the pack is connected to an external power supply, the pack may charge both the pack battery and an e-cigarette battery simultaneously, i.e. some electrical power from the external source is directed to the pack battery, while at the same time, some electrical power from the external source is directed to the e-cigarette for re-charging the battery within the e-cigarette.
It is desirable for the operation and (re)charging of an e-cigarette and associated pack to be as safe, reliable and convenient for a user as possible.